1. Field of the Invention
The present invention relates to an image storage and display system including an image server, which stores image data, and a display terminal, which is connected to the image server via a network, and an image storage and display method that is executed by the image storage and display system. The invention also relates to a maintenance system that maintains such an image storage and display system with remote control.
2. Description of the Related Art
In the medical field, various diagnostic image generating apparatuses (modalities) using an X-ray computed tomographic (CT) apparatus, an X-ray Digital Radiography (DR) apparatus, and a magnetic resonance imaging (MRI) apparatus, an ultrasonic diagnostic apparatus, and the like are used. Image data generated by these modalities are displayed on display devices such as CRTs and LCDs and used for various diagnoses in medical sites.
In accordance with advances of the communication technologies and the computer technologies in recent years, a network using computers is established in a hospital. Moreover, the network is connected to institutions on the outside such as diagnostic reading centers and system maintenance companies. In this case, the modalities and the CRTs and the LCDs constitute a part of the network as image input apparatuses and the image display terminals, respectively.
Other than the image input devices and the image output devices, this network includes an image server including a storage such as a hard disk for storing image data generated by the image input devices. The image display terminals acquire images from the image server as required and display the images. Then, users like doctors and nurses change qualities, arrangements, display information, and the like of the images and refer to or diagnostically read the images to determine and confirm medical policies for patients.
In order to store image data as much as possible in the storage of the image server, usually, compressed image data are stored. The image display terminals request the compressed images from the image server via the network and expand the acquired compressed image to display medical images. A compression method and a compression ratio used for the compression are determined at the time of system construction, that is, before operation is started.
In such a system, an image characteristic may be different for each of the modalities and a resolution may be different for each of the image display terminals. Thus, considerably long time is required for initial adjustment of parameters such as the compression ratio that affect a quality of images.
However, after the parameters such as the compression ratio are set at the time of system construction, it is impossible to confirm whether the setting is correct. Therefore, the parameters are used without change even if the parameters are not optimum parameters. In addition, even if a change of the parameters is required in operation, since it is not clear according to what kind of standard and information the parameters should be changed, the parameters cannot be changed optimally. For example, it is inefficient to store an image according to a compression method with a low compression ratio in order to give priority to a quality of the image, because a large storage area is required. Conversely, if priority is given to efficiency of a storage, a user may be dissatisfied because an image quality is low.
Therefore, under the present situation, at the time of diagnostic reading of an image, the user adjusts the compression ratio of the image with reference to various kinds of image information every time when the user is dissatisfied with a quality of the restored image.
On the other hand, for example, JP-A-2002-352220 proposes an image storage system having the object of transferring image data promptly. In the image storage system, an image server generates image data of three versions, namely, original image data Sorg and irreversible compressed image data S1 and S2, for one image, and temporarily stores the image data in a storage medium. A work station connected to the image server via a network designates a version of image data to be acquired. The image data of the designated version is temporarily read out from the storage medium and transferred to the work station and an image based on the image data is displayed on a monitor.
In this system, it is possible to temporarily delete the original image data Sorg from the storage medium after a predetermined period has elapsed by storing the original image data Sorg in an archive. However, this only makes it possible to select one of two kinds of images of different compression ratios but does not make it possible to designate a compression ratio. Thus, it is still impossible to set an optimum compression ratio.